During the early 1950s, Robert Rauschenberg began using found objects and images in his paintings, resulting in his Combines series. He called Untitled the first true Combine, as it joins several two-dimensional planes into a three-dimensional artwork, making it a hybrid of sculpture, painting, and assemblage. Its structure invites the viewer to look into and through its spaces; front and back openings, scrims that simultaneously reveal and obscure, and mirrors that reflect and reconfigure draw the eye around the work, and a web of meaning is constructed through layers of imagery. Untitled also illustrates the artist’s interest in collaboration; the collaged panel of the upper box features drawings by two of his contemporaries, Cy Twombly and Jack Tworkov.

I called them all Combines. I had to coin that word because I got so bored with arguments. I was interested in people seeing my work.... If I said “It is painting,” they would say, “That’s not painting, it’s sculpture.”... The word “combine” really refers to those things that somehow exceed the traditional or the former definition of a painting.
—Robert Rauschenberg